History
A 3-year-old sexually intact male Pug with a body weight of 13.2 kg (29 lb) was admitted to the Veterinary Teaching Hospital of the University of Trás-os-Montes e Alto Douro with unilateral enlargement of the scrotal contents of 10 days' duration. There was no history of trauma and no other clinical concerns reported by the owners. Clinical examination revealed enlargement of the left side of the scrotum. Palpation revealed that the contents of the left side of the scrotum were turgid; furthermore, palpation did not elicit signs of pain. Contents of the enlargement could not be reduced through the inguinal canal. Palpation of the right side of the scrotum, including the right testis and epididymis, did not reveal any abnormalities. No other clinical signs were detected during physical examination. Results of hematologic and biochemical analyses were within reference ranges.
Question
What are the differential diagnoses for scrotal enlargement in dogs? Please turn the page.
Answer
Orchitis and epididymitis (including infection with Brucella canis), spermatocele or sperm granuloma, inguinal hernia, hydrocele, trauma, and testicular neoplasia.
Results
Ultrasonography was performed. The right testis was of normal size and shape (oval; length, 27.9 mm; width, 17.5 mm; and height, 18.0 mm). It had a homogenous, slightly granular echotexture with a centrally located mediastinum (Figure 1). The epididymis was of normal size and echogenicity.
Ultrasonographic images of the right (A) and left (B) testes of a 3-year-old Pug with unilateral enlargement of the left side of the scrotum. The right testis appears to be normal in size, shape, and echogenicity, whereas the left testis is rounded and hypoechogenic. Length of the right and left testes (distance between the x's) is 27.9 and 20.2 mm, respectively, and width of the right and left testes (distance between plus signs) is 17.5 and 17.2 mm, respectively. A hyperechoic structure (asterisk) is located adjacent to the cranial pole of the left testis, and anechoic fluid (dagger) is evident in the vaginal cavity.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Ultrasonographic images of the right (A) and left (B) testes of a 3-year-old Pug with unilateral enlargement of the left side of the scrotum. The right testis appears to be normal in size, shape, and echogenicity, whereas the left testis is rounded and hypoechogenic. Length of the right and left testes (distance between the x's) is 27.9 and 20.2 mm, respectively, and width of the right and left testes (distance between plus signs) is 17.5 and 17.2 mm, respectively. A hyperechoic structure (asterisk) is located adjacent to the cranial pole of the left testis, and anechoic fluid (dagger) is evident in the vaginal cavity.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Ultrasonographic images of the right (A) and left (B) testes of a 3-year-old Pug with unilateral enlargement of the left side of the scrotum. The right testis appears to be normal in size, shape, and echogenicity, whereas the left testis is rounded and hypoechogenic. Length of the right and left testes (distance between the x's) is 27.9 and 20.2 mm, respectively, and width of the right and left testes (distance between plus signs) is 17.5 and 17.2 mm, respectively. A hyperechoic structure (asterisk) is located adjacent to the cranial pole of the left testis, and anechoic fluid (dagger) is evident in the vaginal cavity.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
The left testis (length, 20.2 mm; width, 17.2 mm; and height, 17.7 mm) was substantially smaller than the right testis. The left testis was slightly rounded in the longitudinal plane (rather than a normal elongated oval shape) and was hypoechoic (Figure 1). An extratesticular moderately hyperechoic structure with an irregular shape and borders was detected adjacent to the cranial pole of the testis (Figure 2). No loops of bowel were seen.
Ultrasonographic image of the left side of the scrotum of the dog of Figure 1. See Figure 1 for key.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Ultrasonographic image of the left side of the scrotum of the dog of Figure 1. See Figure 1 for key.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Ultrasonographic image of the left side of the scrotum of the dog of Figure 1. See Figure 1 for key.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Color flow Doppler ultrasonography revealed poor blood flow to the left testis (Figure 3). A moderate amount of fluid was found in the vaginal tunic surrounding the left testis.
Color flow Doppler ultrasonographic images of the testicular artery of the right (A) and left (B) spermatic cords. There is poorer blood flow to the left testis, and a hyperechoic structure in the vaginal cavity of the left testis also can be seen.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Color flow Doppler ultrasonographic images of the testicular artery of the right (A) and left (B) spermatic cords. There is poorer blood flow to the left testis, and a hyperechoic structure in the vaginal cavity of the left testis also can be seen.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Color flow Doppler ultrasonographic images of the testicular artery of the right (A) and left (B) spermatic cords. There is poorer blood flow to the left testis, and a hyperechoic structure in the vaginal cavity of the left testis also can be seen.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
On the basis of the findings (an abnormal hyperechoic structure within the scrotum, hydrocele, and testicular congestion), inguinal hernia was tentatively diagnosed. Surgery was recommended to correct the condition.
The dog was premedicated by IM administration of morphine (0.2 mg/kg [0.09 mg/lb]) and acepromazine maleate (0.01 mg/kg [0.0045 mg/lb]). Anesthesia was induced by IV administration of diazepam (0.2 mg/kg), ketamine hydrochloride (0.5 mg/kg [0.23 mg/lb]), and propofol (4 mg/kg [1.82 mg/lb]). Anesthesia was maintained thereafter with isoflurane.
Surgery began with a midline incision, caudal to the umbilicus and measuring approximately 10 cm in length. Surgical exploration revealed that omentum and fat were passing through the left inguinal canal, but because of adhesions to the left testis, reduction of the hernia contents was not possible. A decision was then made to perform scrotal ablation and orchiectomy. An incision was made around the base of the scrotum (Figure 4), and careful dissection of the spermatic cord was performed as proximal as possible; the spermatic cord was ligated and transected near the inguinal ring. Closure of the incisions was performed routinely.
Photograph of the inguinal area obtained during surgery to repair the hernia. Notice the omentum and fat that protrude through the left inguinal ring (arrow) as well as the pars longa glandis of the penis (dagger).
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Photograph of the inguinal area obtained during surgery to repair the hernia. Notice the omentum and fat that protrude through the left inguinal ring (arrow) as well as the pars longa glandis of the penis (dagger).
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Photograph of the inguinal area obtained during surgery to repair the hernia. Notice the omentum and fat that protrude through the left inguinal ring (arrow) as well as the pars longa glandis of the penis (dagger).
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
The left testis appeared to be nonviable, congested, and atrophied (Figure 5). Histologic examination of both testes revealed hemorrhagic infarction and complete destruction of architecture of the left testis. Microbiological culture of testicular tissues did not yield any pathogenic agents.
Photograph of the testes and scrotum after surgical removal from the dog of Figure 1. Notice that the left testis (asterisk) is hemorrhagic and atrophied and adhered to the hernia contents. The right testis has a normal appearance. Bar = 25 mm.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Photograph of the testes and scrotum after surgical removal from the dog of Figure 1. Notice that the left testis (asterisk) is hemorrhagic and atrophied and adhered to the hernia contents. The right testis has a normal appearance. Bar = 25 mm.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Photograph of the testes and scrotum after surgical removal from the dog of Figure 1. Notice that the left testis (asterisk) is hemorrhagic and atrophied and adhered to the hernia contents. The right testis has a normal appearance. Bar = 25 mm.
Citation: Journal of the American Veterinary Medical Association 252, 8; 10.2460/javma.252.8.933
Discussion
The cause of scrotal enlargement requires an accurate and timely diagnosis to enable treatment to be rapidly initiated, considering that complications could soon arise. A systematic approach to the diagnosis is essential. Several conditions could cause scrotal enlargement in dogs. Differential diagnosis should address factors such as the history and rate of onset, whether the enlargement is unilateral or bilateral, and whether scrotal inflammation and signs of pain or other clinical signs are detected during physical examination.
Acute orchitis or epididymitis is more common in young dogs. In addition to unilateral or bilateral scrotal edema, heat in the affected area, and signs of pain, other clinical signs could include fever, lethargy, a hunched posture, and purulent penile discharge.1,2 Spermatic cord torsion is a less common cause of scrotal enlargement. Clinical signs are severe and include acute signs of abdominal pain, lethargy, anorexia, vomiting, dysuria, hematuria, and fever.1,2 This condition leads to ischemia and should be treated as a surgical emergency. Neoplasia of a descended testis is more common in old dogs but should always be considered whenever there is a change in the shape and size of a testis. Testicular neoplasia often is evident as an insidious and nonpainful enlargement of the scrotal contents, which is accompanied by atrophy of the contralateral unaffected testis owing to an increase in temperature of the affected testis and exacerbated production of hormones.1
Hydrocele (accumulation of fluid in the vaginal tunic) and spermatocele or sperm granuloma are rare conditions that progress slowly; they are evident as a scrotum with turgid nonpainful distention.2,3 Spermatoceles are evident clinically as firm nonpainful dilatations of the epididymis.2
Inguinal hernias result from a defect in the inguinal ring through which abdominal contents protrude. Several factors (eg, anatomic defects of the inguinal ring orifice and traumatic events) may be involved in the pathogenesis of inguinal hernias.4 Initial clinical signs are attributable to protrusion of abdominal contents and can include unilateral edema and signs of pain. If the condition is not resolved, more severe signs could become evident, such as those related to strangulation of the abdominal contents and vascular obstruction at the inguinal ring.5
Diagnosis of the cause of a scrotal enlargement should begin with a complete medical history because an acute onset with signs of pain is more likely to be associated with torsion of the spermatic cord, herniation, or acute inflammation. In contrast, progressive enlargements unaccompanied by signs of pain are more likely to be associated with neoplasia.
Palpation allows evaluation of the scrotal wall and scrotal contents in the region extending from the tip of the scrotum to the external inguinal ring. Palpation of the testes allows evaluation of the size, shape, consistency, and temperature of the testes and determination of whether signs of pain are elicited. Palpation can also be used for evaluation of the epididymides.
Evaluation of the medical history and results of the physical examination should lead to creation of a list of differential diagnoses. Ultrasonography (B-mode and color flow Doppler) could be used to achieve a definitive diagnosis. Ultrasonography is the method of choice for determining the specific cause of scrotal enlargement because it allows clinicians to determine the degree of involvement for each of the scrotal structures (scrotum, vaginal tunic, testes, epididymides, and spermatic cords) and inguinal area.
In the dog of the present report, conditions with an acute onset (eg, spermatic cord torsion and acute orchitis or orchiepididymitis) were initially excluded on the basis of the medical history (the condition apparently did not have a sudden onset) and because palpation did not elicit signs of pain. Also, hydrocele was ruled out on the basis of the absence of thickening of the scrotal wall, a consistent clinical sign of this condition.3
A testicular tumor could not be excluded, despite the fact the dog was only 3 years old. The contralateral testis had a normal size and consistency. A chronic process (eg, chronic orchitis or epididymitis) could not be excluded initially; the testis and scrotal contents were not freely movable within the scrotum, which could have indicated the existence of adhesions. Inguinal hernia was also considered a possibility.
Ultrasonographic examination of the scrotal and inguinal region was performed. A clinically normal right testis was evident (homogeneous and moderately hyperechoic parenchyma, with the mediastinum appearing as a central hyperechoic line). In this dog, ultrasonography allowed detection of the mass in the vaginal tunic and the ability to search for other findings, such as accumulation of fluid, hydrocele, and bowel loops. Color flow Doppler ultrasonography allowed the assessment of blood flow of the testicular artery in the spermatic cord and affected testis and comparison with flow in the unaffected testis. Consideration of all the findings led to the final diagnosis of inguinal hernia.
Inguinal hernias generally denote direct and indirect hernias.5 A direct inguinal hernia results when the abdominal contents protrude through a weak spot of the fascia in the caudal wall of the inguinal canal. Indirect inguinal hernias, as in the dog described here, can be the result of a congenital defect in the vaginal ring, which in males may be attributable to late descent of the testes into the scrotum and delayed narrowing of the inguinal ring.5 This allows abdominal contents to protrude into the vaginal tunic alongside the contents of the spermatic cord.5 There are severe risks and complications (eg, incarceration, obstruction, and strangulation of prolapsed tissues) associated with indirect inguinal hernias. Another risk is impairment of the testicular vascular supply owing to compression of both the spermatic artery and vein by the herniated structures. The testes are sensitive to vascular and temperature changes; thus, fertility following scrotal enlargement is uncertain.6
The dog described here did not manifest signs of pain during palpation of the scrotal contents and inguinal region. Contents of an inguinal hernia usually include fat, omentum, and intestine. In the dog of the present report, only fat and omentum were contained in the hernia contents, which could have contributed to the lack of other clinical signs.7 However, adhesions were already present in the scrotum. The presence of hydrocele (an accumulation of serous fluid in the vaginal tunic secondary to the hernia) could have been attributable to compromise of lymphatic drainage.
Resolution of an inguinal hernia should, whenever possible, involve preservation of the testes and reduction of hernia contents with imbrication of the vaginal process and inguinal ring. However, there can be a recurrence of a hernia. In the dog described here, it was not possible to use that surgical technique because of the scrotal adhesions to the vaginal tunica, which did not allow preservation of the scrotum and necessitated bilateral orchiectomy. However, for dogs in which the scrotum can be preserved, unilateral castration could be considered as a means of preserving reproductive ability.
Outcome
The dog received methadone (0.2 mg/kg, IM, q 6 h for 24 hours) for pain and amoxicillin and clavulanic acid (25 mg/kg [11.36 mg/lb], PO, q 12 h for 5 days) to prevent infection after surgery. Postsurgical recovery was uncomplicated, and the dog was discharged 3 days after surgery.
References
1. Johnston SD, Root Kustritz MV, Olson PNS. Disorders of the canine epididymis. In: Johnston SD, Root Kustritz MV, Olson PNS, eds. Canine and feline theriogenology. Philadelphia: Saunders, 2001;312–332.
2. Mir F. Asymétrie testiculaire chez le chien. Point Vétérinaire 2013;335:24–28.
3. Johnston SD, Root Kustritz MV, Olson PNS. Disorders of the canine scrotum. In: Johnston SD, Root Kustritz MV, Olson PNS, eds. Canine and feline theriogenology. Philadelphia: Saunders, 2001;333–336.
4. Waters DJ, Roy RG, Stone EA. A retrospective study of inguinal hernia in 35 dogs. Vet Surg 1993;22:44–49.
5. Smeak DD. Abdominal wall reconstruction and hernias. In: Tobias K, Johnston SA, eds. Veterinary surgery small animal. St Louis: Elsevier, 2011;1353–1379.
6. Morresey PR. The enlarged scrotum. Clin Tech Equine Pract 2007;6:265–270.
7. Ravikumar S, Ranganath L. Surgical management of inguinal hernia in a male dog. Indian J Canine Pract 2014;6:53–55.
